1. Field of the Invention
The invention relates to a ball throwing machine for the improvement of tennis and baseball skills. In particular, it comprises a relatively simple and inexpensive machine that throws or propels a ball in a manner that simulates actual play.
2. Description of the Prior Art
Known ball throwing machines may be classified into several categories depending on the motive force utilized to propel the ball.
An example of the most popular and commercially accepted ball throwing machine is disclosed in U.S. Pat. No. 4,291,665, issued Sept. 29, 1981, to Bash et al. The Bash teaching is typical of a family of ball throwers that utilize compressed air or other gas to eject the balls from a tightly fitting barrel. Inherent problems with this design are:
(1) Extreme and unpredictable ball velocity. New balls fit tightly in the barrel, whereas old balls allow air to escape. Thus, balls are propelled at unpredictable velocity and distances.
(2) Compressed air requires relatively large amounts of power, necessitating that a high amperage source of 120 VAC power be available to the machine.
(3) The machinery is complex, requires many moving parts and is relatively heavy.
(4) Machines of this design are not easily converted to propulsion of baseballs as the stitches on a baseball preclude a sealing fit with the barrel of the machine.
Other patents in this group are U.S. Pat. Nos. 3,838,676 and 3,989,254.
Another family of ball throwing machines utilizes a spinning wheel. An example is taught in U.S. Pat. No. 4,423,717, issued Jan. 3, 1984, to Kahelin. The disadvantages common to this class of machines are:
(1) complex machinery, resulting in relatively high weight and large numbers of rapidly moving parts;
(2) the moving wheel utilizes friction to rapidly accelerate the projectiles which erodes the surface of the balls, and rapidly wears tennis balls; and
(3) a substantial AC power requirement.
Other patents in this class are U.S. Pat. Nos. 3,844,267; 4,423,717; and 4,025,071.
Yet another class of ball throwing machines is represented by U.S. Pat. No. 4,269,162, issued May 26, 1981, to Abraham et al. The Abraham machine uses an arm to fling or strike the balls. As a rapidly moving arm also requires complex and expensive machinery, this design shares the disadvantages of weight, cost, power consumption, and lack of portability with each of the classes previously discussed. Other patents in this class are U.S. Pat. Nos. 3,659,576; 3,779,227; 4,237,851; 4,262,648; and 4,368,885.
Yet another class of ball throwing machines, and the one into which the present invention falls, are machines that utilize a spring to eject the ball from a barrel. For example, the patent to Politzer U.S. Pat. No. 3,128,753, issued Apr. 14, 1964, teaches the use of a spring driven piston wherein the spring is cocked by a motor driven cam. U.S. Pat. No. 3,807,379, to Vodinh, issued Apr. 30, 1974, teaches cocking of a spring by a solenoid. Other patents of interest in this class are U.S. Pat. Nos. 2,701,558; 2,921,574; 3,850,157; and 4,227,508.
The present invention constitutes an improvement on the aforesaid teachings.